26: Acute Abdominal Pain

Key Points

• primary survey should be conducted to rapidly screen for vascular catastrophes, abdominal sepsis, or perforated viscus.

• Appendicitis should always be on the differential diagnosis for acute abdominal pain.

• Females of childbearing age with abdominal pain are presumed to have an ectopic pregnancy until proven otherwise.

• Older and immunocompromised patients may have an atypical presentation of disease.

• The white blood cell count is an unreliable predictor of disease and should not be used in isolation to confirm or exclude a critical diagnosis.

Introduction

Abdominal pain is a common presenting complaint and represents up to 10% of all emergency department (ED) visits. Although the etiology of abdominal pain frequently goes undiagnosed, the role of the emergency physician is to first identify and treat any immediate life- or organ-threatening conditions. Imminent causes of abdominal pain that need to be promptly diagnosed are those driven by a vascular event, infectious process, or perforated viscous (eg, ruptured abdominal aortic aneurysm [AAA], cholangitis, perforated gastric ulcer). Other disease processes may not pose an immediate threat to the patient but should be diagnosed before discharge, as delays in treatment can result in patient morbidity (eg, appendicitis, pelvic inflammatory disease).

Abdominal pain can be classified as visceral, parietal, or referred in origin. Depending on the disease process, pain may begin as visceral and become parietal, as in the stretching and subsequent rupture of a hollow viscus. Visceral pain occurs with the stretching of nerve fibers in the walls of hollow organs or the capsules of solid organs. The location of pain is not well localized, but often has an embryologic basis that aids in determining the diagnosis. Epigastric pain occurs in patients with stretching of foregut organs (stomach to duodenum, including biliary tree and pancreas). Periumbilical pain represents pathology of midgut organs (distal duodenum to transverse colon). Suprapubic pain is due to problems of the hindgut organs (distal transverse colon, rectum, and urogenital tract). Parietal pain is due to irritation of the parietal peritoneum. The patient is more readily able to localize the pain (eg, left lower quadrant pain in diverticulitis), but when the entire peritoneal cavity is involved, the pain is diffuse. Referred pain is defined as pain experienced at a site distant from its source. Its anatomic basis lies in afferent nerves from different locations sharing the same spinal cord segment. Abdominal pain may be referred from organs above the diaphragm (eg, myocardial infarction causing epigastric pain). Alternatively, abdominal pathology may refer pain to sites above the diaphragm (eg, splenic rupture causing shoulder pain).

Older and immunocompromised patients warrant special consideration as higher risk groups. Older patients have a greater incidence of vascular catastrophes and surgical disease, with as high as 40% of patients older than 65 years requiring operative intervention (Table 26-1). Compared with younger counterparts, older patients are more likely to have atypical presentations, have nonspecific symptoms, and ...